How to Measure Quad Lag

This article is a summary of Dr. Mario Walther (see sources below).

What is the best way to measure the force in production and why is it important?

Action forces that are used in production can represent risk factors for the development of health disorders. This risk increases significantly with age and can therefore increase sickness-related absenteeism. As a result, companies that are supposed to pay the high costs of poor or nonexistent ergonomic measures are also affected.

It is therefore important to give priority to people and their health by identifying and eliminating risk factors at an early stage!

In order to be able to measure these action forces practically with human influence and to be able to carry out effective measures, the use of ergonomists at the workplace with force measuring devices is most common. These measurements provide objective, detailed and precise results of the stress levels on the human body. To do this, they need the most precise measuring devices.

High forces are exerted by hand

Most of the force is expended in production or in the assembly area, with around 2400 effort per shift. The joining of snap connections, plugs and panels is associated with repetitive and high hand and finger forces and represents a fairly high risk for the fitters. The high action forces, constrained postures and insufficient rest breaks can lead to health damage. The dimensions and material of the assemblies also play a decisive role in the expenditure of force.

The early consideration of ergonomic aspects can lead to improvement measures that can reduce or prevent the risk factors. For example, by developing assembly-compatible components in the design phase, companies can significantly reduce the required joining forces and workplaces and tools can be designed more ergonomically.

In order to take these ergonomic elements into account, it is necessary to carry out practical measurements that primarily define the actual joining force.


Why does the joining force not correspond to the impact force?

It is important to distinguish the joining force from the impact force. The joining force is the force required to assemble a component. The force exerted by the test person after the insertion is the impact force or the holding force. Due to the short period of time that a fitter has for his task, he can often not reduce his effort sufficiently. When the applied force approaches the force to be applied, the work is done efficiently. Otherwise the effort can lead to illness of the fitter.

If you use a force measuring device for ergonomic measurement that only measures the maximum, the joining force is not determined, but the impact force. The assembly forces imply high-frequency vibrations that are in the range of approx. 250 Hz: a measurement frequency that is too low does not allow the difference between the joining and impact force to be determined due to the fast assembly process. This leads to a lack of feedback about the performed joining process and can lead to more effort.

The solution: the Centor Touch force gauge

The Andilog Centor Touch force measuring device is a flexible and sophisticated solution for practical measurements in production areas. This cost-effective, robust and very precise force measuring device is equipped with strain gauges and enables quick measurements without disrupting work processes.

The Centor Touch measures with a sampling rate of 5,000 Hz, which enables the measurement of the smallest force fluctuations. It offers automatic calculations such as the first break (joining force) and the maximum of the entire test (impact or holding force). The curve progression is shown in real time on the display: this means that the test person can judge immediately after the measurement whether it was carried out correctly. Adjustable force thresholds in the Centor Touch enable the force to be entered: the test subject receives an acoustic signal when he has reached the target value and can stop the measurement.

Since the direction of force influences the measurement, Andilog has developed pressure plates with small dimensions (Ø20 and 8 mm) that support the test subject in his measurement on the ideal joining axis. The values ​​determined are extremely precise and the calibration certificate supplied guarantees an accuracy of 0.1% of the entire sensor measuring range.

Results of the measurements with the Centor Touch

The Centor Touch offers a very good cost-benefit ratio with a realistic test speed. The measurement starts manually after applying a previously defined force and ends automatically after a defined period of time.


Conclusions

Concrete ergonomic measures can only be carried out on the basis of concrete measurement results. However, you also need the sensitization and benevolence of the employees and managers concerned. In this way, employees can optimize their use of force and keep it as low as possible, but as high as necessary. The departments that deal with product development can design the properties and materials of their components in such a way that the high forces of action are reduced or even prevented. As a partner for ergonomics, Andilog offers a compromise between high-precision measurement and flexible operation directly on the assembly line.

Ergonomics is the result of collaboration between all departments and partners in a company. It plays an essential role in the process of making people the main resource in companies and restoring their health and value creation potential. Andilog sees itself as an actor and partner in this area.

 

source: Mario Walther, 2015, development and evaluation of a systematic procedure for recording action forces in automobile production, approved dissertation for obtaining the academic degree of doctoral engineer, Faculty of Mechanical Engineering at the Technical University of Chemnitz

Document available at on the qucosa website.